Dot writing head for high definition printers, and a method of manufacturing the same

Abstract

The head is composed of a series of electrically conductive elements in one or more rows, which elements are selectively subjected to a high potential relative to the coacting electrode. The elements have a thickness of less than to 50μ and a pitch less than 100μ. The elements may be disposed in a plurality of rows on a cylindrical, rotatable head. In a modified embodiment the elements are disposed on the edge of a plate, in a row extending over the length of the line.

I claim: 
     
       1. A dot writing head for high definition printers, in which the writing elements are electrical conductors and are activated by selectively subjecting them to a high electrical potential relative to the potential of a coacting electrode, characterised in that the writing surface of these elements has a dimension not greater than 50μ, the elements being disposed on the cylindrical surface of a wheel in a plurality of parallel rows, the pitch of the elements on a row being not greater than 100μ, the pitch of the rows being not greater than 100μ, and characterized in that the elements of a row are formed by a sheet comprising a metallic layer of a thickness of 20 to 30μ and a layer of polyester of a thickness of 20 to 50μ, this sheet having a comb-like edge. 
     
     
       2. A head as claimed in claim 1, characterised by a plurality of the said sheets in a stack, each sheet being electrically connected to an insulated conductor passing through a hole in the sheets lying above it, these wires passing through the said holes inside an insulating tube. 
     
     
       3. A head as claimed in claim 1, characterised in that the said sheets are vitrified and that the writing edge of the said head is lapped and profiled so as to reduce friction against the printing support. 
     
     
       4. A head as claimed in claim 1, characterised in that the said comb-like edge is produced by photoincision of the metallic layer. 
     
     
       5. A head as claimed in claim 4, characterised in that the said sheets are assembled between two rigid flanges with the aid of a polyester resin based thermoplastic adhesive tape. 
     
     
       6. A head as claimed in claim 4, characterised in that on the said sheet are mounted integrated semiconductor logic and power circuits for the control of the said elements, a series of connections between the said elements and the said circuits being obtained by the aforesaid photoincision.